Control through parallel port of digital signals

[olsonj112]

I have an control application that I hope to be able to use the parallel port to control. The plant is a model of an industrial process system with simple on/off sensors and on/off actuators. I hope to be able to input 7 sensor signals and output 5 actuator signals via the parallel port. The sensors will be changing non-deterministically and will be polled continously in order to change the output actuators. Essentially, I will need to read a byte of sensor data and output a byte for the actuators. Based on my research into LabVIEW I believe this will work; however, our computer support group has not been able to install LabVIEW on my machine yet. I've looked at the tutorials available but want to verify the validity of my application with the material available from NI. My question is, Does this application seem reasonable to be done using LabVIEW? I've looked at the tutorials available but want to verify the validity of my application with the material available from NI. I've spent too much time finding a way to do this, to end up going down yet another dead end road. BTW, the machine I use is Windows 2000 with LabVIEW 7.0.

Thanks in advance.

[ian_fung]

hi olsonj112,

Yes, indeed, you would be able to use parallel port as I/O and completely done in LabVIEW.

I have been working on projects using parallel port as I/O for relay switching, High/Low (TTL) measurement i.e. Sensors with TTL outputs. However, before doing so, you might wanna go through the following links for better understanding of parallel port configuration etc.

Using the Parallel Port as an Input/Output Channel
Using the Parallel Port in LabVIEW


Also, Port and Memory Utilities for Windows might be necessary!

Port and Memory Utilities for Windows

CHeers!
Ian F K
Ian.F

Message Edited by ian.f on 03-02-2005 10:38 PM

Message Edited by ian.f on 03-02-2005 10:43 PM

Message Edited by ian.f on 03-02-2005 10:44 PM

[Steven_H.]

It is certainly reasonable to use LabVIEW for this application.

If the sensor signals are analog, you'll need a multifunction DAQ board to digitize them, and the parallel port is a definite no-go.

If the sensor signals are digital, the parallel port may be an option. Here is a good reference that explains some of the issues you'll face if you choose that approach.

If it were me, I'd buy a basic digital I/O board like the PCI-6503. This assumes that simple TTL and low-speed, software-timed I/O is adequate for your application.

Steven H.

[olsonj112]

Thanks Ian, sounds like our applications are similar. In fact, my application was designed to be controlled by PLC ladder logic similar to what you're doing. My goal is to be able to implement the same controller using a different technology as part of my master's thesis.

[ian_fung]

hi hi
I should have got my master then 😛
Well.. I am just making a living...

Cheers!
ian

[Marce]

Hello,

Just a comment about parallel ports.

Some time before I met LV I had a simple project where a biometric sensor would open a door for the right people. I used the parallel port to output the signal to the relay that would open the electric lock. Everything worked perfect until there was a energy problem, the no-break discharged and the computer reboot. Then I realized that that specific computer, when starting to work and before my program started to run, sends a series or strange ONs and OFFs to the PINs of the parallel port and that action just opened the door. We solved that problem with adding analog logics to the relay circuit but I was never happy with that solution. BTW, in my notebook, where I developed the system, the parallel port behaved very well and was completely quiet in the boot time.

I will surely try using the parallel port, within LV, in future projects but ...

Any comments?

Thanks,

Marcelo